1. Field of the Invention
The present invention relates to an optical fiber used for optical transmission such as wavelength division multiplexing transmission or the like in a wavelength band of 1.5 xcexcm, an optical transmission line using the optical fiber, and an optical transmission system.
2. Background of the Invention
Development of information society is promoting rapid increase of communication information quantity. Such an increase of information makes people pay attention to techniques for WDM (wavelength division multiplexing) transmission and TDM (time division multiplexing) transmission. The WDM transmission is a system for transmitting plural lights of different wavelengths through a single optical fiber, and thus it is an optical transmission system suitable for large-capacity and high bit-rate communications. Recently, the techniques for the wavelength division multiplexing transmission have been actively studied.
Recently, it has been considered that the wavelength division multiplexing transmission is carried out in a wavelength band of 1.55 xcexcm which corresponds to a gain band of an erbium-doped optical fiber amplifier (EDFA). The wavelength band of 1.55 xcexcm is a wavelength band having a center wavelength of 1550 nm like a wavelength band from 1530 nm to 1570 nm.
Therefore, the present invention is to provide an optical fiber having the following construction and an optical transmission line using the optical fiber, and an optical transmission system.
An optical fiber according to the present invention is characterized in that the chromatic dispersion value thereof at a wavelength of 1.55 xcexcm is set to a value in the range of 4 ps/nm/km to lops/nm/km and the cutoff wavelength thereof is set to a value in the range of 1.3 to 1.4 xcexcm.